NAKED


Write functions without prolog/epilog code

Syntax:
{Sub | Function} identifier Naked [calling_convention] ( param_list ) [[ Byref ] As data_type]
asm_statements
End {Sub | Function}

Parameters:
identifier - name of the procedure.
calling_convention - calling convention of the procedure - can be CDecl, Pascal, or StdCall
asm_statements - the code in the procedure body. The code for handling parameters and returning values must all be done manually. Note that the methods for doing these can change, depending on the calling convention.
param_list - parameters to be passed to the procedure.
data_type - the data type of the function.

Description:
Naked allows the programmer to write procedures without the compiler generating any prolog/epilog code. This is useful when writing small, fast functions in Asm without any unnecessary overhead.

Examples:
'' Naked cdecl function
Function subtract_c Naked CDecl _   '' parameters pushed onto call stack in reverse order of declaration
    ( _
        ByVal a As Long, _
        ByVal b As Long _        '' parameter pushed onto stack in first
    ) As Long
   
    Asm
        mov eax, dword Ptr [esp+4]  '' eax = a
        Sub eax, dword Ptr [esp+8]  '' eax -= b
        ret                         '' return result in eax
    End Asm
   
End Function

Print subtract_c( 5, 1 ) '' 5 - 1

''---------------------------------------------------------------------------------------------------------------------

'' Naked stdcall function
Function subtract_s Naked Stdcall _ '' parameters pushed onto call stack in reverse order of declaration
                         _          '' called procedure responsible for removing parameters from stack
                         _          ''   (appending constant to RET instruction specifying number of bytes to release)
    ( _
        ByVal a As Long, _
        ByVal b As Long _        '' parameter pushed onto stack in first
    ) As Long
   
    Asm
        mov eax, dword Ptr [esp+4]  '' eax = a
        Sub eax, dword Ptr [esp+8]  '' eax -= b
        ret 8                       '' return result in eax and 8 bytes (2 integers) to release
    End Asm
   
End Function

Print subtract_s( 5, 1 ) '' 5 - 1

''---------------------------------------------------------------------------------------------------------------------

'' Naked pascal function
Function subtract_p Naked Pascal _  '' parameters pushed onto call stack in same order as declaration
                         _          '' called procedure responsible for removing parameters from stack
                         _          ''   (appending constant to RET instruction specifying number of bytes to release)
    ( _
        ByVal a As Long, _       '' parameter pushed onto stack in first
        ByVal b As Long _
    ) As Long
   
    Asm
        mov eax, dword Ptr [esp+8]  '' eax = a
        Sub eax, dword Ptr [esp+4]  '' eax -= b
        ret 8                       '' return result in eax and 8 bytes (2 longs) to release
    End Asm
   
End Function

Print subtract_p( 5, 1 ) '' 5 - 1

'' Naked cdecl function
'' plus ecx register preserved in asm block by creating user stack
Function subtract_cp Naked CDecl _      '' parameters pushed onto call stack in reverse order of declaration
    ( _
        ByVal a As Long, _
        ByVal b As Long _            '' parameter pushed onto stack in first
    ) As Long
   
    Asm
        push ebp                        '' push ebp onto stack   => esp -= 4
        mov ebp, esp                    '' ebp = esp
                                        ''    => create user stack 4 bytes above call stack
        push ecx                        '' push ecx onto user stack   => esp -= 4
        mov eax, dword Ptr [(ebp+4)+4]  '' eax = a   (supplementary offset of +4 bytes only due to 'push ebp')
        mov ecx, dword Ptr [(ebp+8)+4]  '' ecx = b   (supplementary offset of +4 bytes only due to 'push ebp')
        Sub eax, ecx                    '' eax -= ecx
        pop ecx                         '' pop ecx from user stack   => esp += 4
        mov esp, ebp                    '' esp = ebp
        pop ebp                         '' pop ebp from stack   => esp += 4
                                        ''    => discard user stack
        ret                             '' return result in eax
    End Asm
   
End Function

Print subtract_cp( 5, 1 ) '' 5 - 1

Platform Differences:
Differences from QB:
See also:
Back to Procedures
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